Low Catalyst Loadings in Olefin Metathesis: Synthesis of Nitrogen Heterocycles by Ring-Closing Metathesis

Kuhn, Kevin M.; Champagne, Timothy M.; Hong, Soon Hyeok; Wei, Wenhao; Nickel, Andrew; Lee, Choon Woo; Virgil, Scott C.; Grubbs, Robert H.; Pederson, Richard L.

doi:10.1021/ol9029808

Cited by 81 publications

(52 citation statements)

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“…2 Following the report of the increased activity of complex 1 (H 2 IMes)(PCy 3 )Cl 2 RudCHPh (H 2 IMes ) 1,3-dimesitylimidazolidine-2-ylidene), 3 and Hoveyda's subsequent exchange of the phosphine ligand with a chelating ether moiety (2), 4 many researchers have focused on increasing catalytic activity, selectivity and stability through modification of the N-heterocyclic carbene (NHC) ligand.…”

Section: Introductionmentioning

confidence: 99%

“…The ligand synthesis and systematic study will aid others in the design of efficient catalytic systems. 2 In the final proposed study, efforts were made to recover and to reactivate the spent catalyst. Methods were found that will allow ruthenium to be recovered efficiently after a reaction but an efficient method to convert the spent system back to an active catalyst was not completed.…”

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confidence: 99%

“…These good results at low temperature and high pressure are well consistent with the batch studies, where the same factors increase the selectivity and yield of ethenolysis. 2 For the ethenolyis of methyl oleate 1, six ruthenium catalysts were selected: first generation catalysts 6 and 7; second generation catalysts 8, 9, and 10; and cyclic alkylamino carbene (CAAC)-based catalyst 11 11 ( Figure 3). Each catalyst was screened at a variety of catalyst loadings, and the results were tabulated (Table 1).…”

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confidence: 99%

“…1 Ruthenium catalysts, which have become useful for organic synthesis and polymer chemistry, have been tested in the olefin methathesis of internal olefins with ethylene, known as ethenolysis, which can be used to produce the desired low molecular weight products from renewable seed oils (eq 1). 2 Early studies of the ethenolysis of natural seed oils showed promise but was limited by the high sensitivity of the traditional molybdenum, tungsten, and rhenium catalysts. The advent of ruthenium catalysts with low sensitivity but high activity has spurred a renewed interest in ethenolysis, but limited selectivity and conversion have hampered progress to commercially viable processes.…”

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confidence: 99%

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The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

Grubbs¹

2013

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Distribution Statement and Applicable Information Approved for public release; further dissemination unlimited.Unclassified; Non-Sensitive• Executive Summary.Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed in this study will be considered for the next generation of operations.• Accomplished objectives and goals.The goal of the research was to develop olefin metathesis catalysts that were highly efficient to be used in the conversion of seed oils into chemical and fuels. We proposed to accomplish this goal by the use of a combination of approaches, increasing the stability of the basic catalysts, isolating them on a surface to slow decomposition and provide a easy mode of isolation and then the development of methods for the reactivation of the supported catalysts should result in a major increase in catalyst efficiency and utility. These catalysts will then have much broader applications in the conversion of naturally occurring olefins into useful products and provide a bio-renewable source of organic molecules. During the support period, a number of supported catalysts were prepared and studied in detail.The utility was sufficiently high that the systems were transferred to a commercial group that is developing applications for the new catalysts. Patented processes were developed and are moving toward commercialization. Through the use of modified ligands, more active and stable catalysts were prepared. These systems have provided a basis for further development of highly active catalyst systems. Some progress was made toward the reactivation of the catalysts. Unfortunately, the funding was completed before that work was finished. It is being carried on using other funds. In addition to the proposed areas, we explored the use of the catalysts in microfluidic systems to explore t...

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Section: Introductionmentioning

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The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

Grubbs¹

2013

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“…[1] In recent years ring-closing metathesis (RCM) [2] has received much attention as a perhaps general method for the synthesis of MRNHs. [3][4][5] While the RCM of N-tethered dienes is well documented, that of N-tethered trienes, which would give access to synthetically attractive double unsaturated MRNHs, has been much less studied. [3,4] Furthermore, the RCM studies of N-tethered dienes and trienes were generally confined to those having a low degree of substitution and functionalization.…”

Section: Introductionmentioning

confidence: 99%

Ring‐Closing Metathesis of Sulfoximine‐Substituted N‐Tethered Trienes: Modular Asymmetric Synthesis of Medium‐Ring Nitrogen Heterocycles

Mahajan

Gais

2011

Chemistry A European J

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A synthesis of sulfoximine-substituted medium-ring nitrogen heterocycles (MRNHs) having a high degree of substitution has been developed. Its key steps are the modular asymmetric synthesis of sulfoximine-substituted N-tethered trienes and their Ru-catalyzed ring-closing metathesis (RCM) reaction. The highly substituted N-tethered trienes were obtained enantio- and diastereopure through 1) the diastereoselective aminoalkylation of sulfoximine-substituted allyltitanium complexes with N-tert-butylsulfonyliminoester, 2) N-allylation of homoallylic N-sulfonyl amines, 3) allylation, hydroxylalkylation, and formylation of α-lithioalkenylsulfoximines, and 4) allylation of α-formylalkenylsulfoximines. The Ru-catalyzed RCM reaction of the sulfoximine-substituted 1,7,10- and 1,7,12-trienes stereoselectively afforded the corresponding nine-, ten-, and eleven-membered MRNHs in good yields. An interesting difference in reactivity was noted in the case of a sulfoximine-substituted 1,7,10-triene and its corresponding 1,10-diene. While the triene readily underwent a RCM reaction, the diene reacted only in the presence of Ti(OiPr)(4) under formation of the corresponding MRNH. The feasibility of a removal of the sulfoximine auxiliary and the N-sulfonyl protecting group from the MRNHs were demonstrated through reduction and cleavage, respectively, of a nine-membered heterocycle, both of which proceeded readily and gave the corresponding cyclic alkene and amine, respectively.

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Dichloro[1,3-bis(2-methylphenyl)-2-imidazolidinylidene](2-isopropoxyphenylmethylene) Ruthenium(II)

Raymond

Collins

2014

Encyclopedia of Reagents for Organic Synthesis

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Low Catalyst Loadings in Olefin Metathesis: Synthesis of Nitrogen Heterocycles by Ring-Closing Metathesis

Cited by 81 publications

References 28 publications

The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

Ring‐Closing Metathesis of Sulfoximine‐Substituted N‐Tethered Trienes: Modular Asymmetric Synthesis of Medium‐Ring Nitrogen Heterocycles

Dichloro[1,3-bis(2-methylphenyl)-2-imidazolidinylidene](2-isopropoxyphenylmethylene) Ruthenium(II)

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